This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-295232, filed Sep. 27, 2000; and No. 2000-296089, filed Sep. 28, 2000.
1. Field of the Invention
The present invention relates to a film-forming method, a film-forming apparatus, and a liquid film drying apparatus used for the coated film formation in the technology, for preparing a semiconductor device in the wafer step and in the step of preparing a mask for the optical exposure and for preparing a liquid crystal device.
2. Description of the Related Art
In the conventional spin coating method employed in a lithography step, a major portion of the coating solution dripped onto the substrate is discharged to the outside of the substrate, and a film is formed of the remaining several percent of the coating solution. As a result, a large amount of the coating solution is rendered useless, and the environment is adversely affected because a large amount of the coating solution is discharged to the outside. An additional problem to be noted is that, when it comes to a rectangular substrate or a disk-like substrate having a large diameter not smaller than 300 mm, turbulence occurs in the outer peripheral portion of the substrate, with the result that the film thickness uniformity is rendered poor this area.
A method for uniformly coating the entire substrate surface with a coating solution without wastage is known. For example, a resist is dripped from a large number of nozzles arranged to form a row, and a gas or a liquid is blown against the film-forming surface from behind the film-forming surface so as to obtain a uniform film. Also, a large number of spurting holes are formed in a rod so as to allow the resist to be dripped uniformly on the substrate and, thus, to obtain a uniform film. Further, a spray head provided with a large number of spurting holes for spraying a resist and the substrate are moved relative to each other so as to achieve a uniform coating.
In each of the conventional coating apparatuses exemplified above, a plurality of dispensing or spraying nozzles are arranged to form a lateral row and scanned along the surface of the substrate so as to form a uniform film on the substrate. Also, there is a method of forming a liquid film by scanning a single liquid discharge nozzle on a target object to be treated in addition to the coating method using an apparatus equipped with these plural nozzles.
However, the conventional coating methods exemplified above give rise to the problem that a thickness distribution of the coated film is generated from the coating starting side toward the coating finishing side. The difficulty is caused by the situation that the coating starting portion and the coating finishing portion widely differ from each other in the waiting time between completion of the coating solution dispensing operation and the drying treatment. It should also be noted that, since it was customary in the past that the step for forming the liquid film and the drying step were carried out independently, a long time was required for completing the coated film.
In the conventional step of drying a liquid film after formation of the liquid film containing a solvent of, for example, a resist film on a target substrate to be processed, employed was, for example, a baking method in which the target substrate is simply heated on a hot plate and a vacuum drying method in which a reduced pressure treatment is applied within a chamber connected to a vacuum pump.
However, in the baking method, since the evaporation of the solvent is highly sensitive to temperature, the thickness uniformity of the coated film was rendered poor, giving rise to a problem in terms of the uniformity of the film thickness.
On the other hand, in the vacuum drying method under a reduced pressure, it takes time to remove the solvent, because of low evaporation rate in reduced pressure, leading to a problem in terms of the low throughput. Also, the throughput is dependent on the properties and the dispensed amount of the solvent, making it impossible to control the processing time.
An object of the present invention is to solve the above-noted problems inherent in the prior art.
According to a first aspect of the present invention, there is provided a film-forming method, comprising dispensing from a dispenser nozzle a coating solution, which is prepared by adding a solid component to a solvent and controlled to be spread on the substrate in a predetermined range, onto a target substrate to be processed while relatively moving the dispenser nozzle and the target substrate so as to form a liquid film on the entire surface of the target substrate; and arranging a sucking nozzle above and apart from the target substrate such that the sucking nozzle is not in contact with the surface of the liquid film so as to permit the sucking nozzle to suck the solvent vapor right under the sucking nozzle while moving the sucking nozzle relative to the target substrate, thereby removing the solvent from the liquid film and, thus, forming a coated film.
According to a second aspect of the present invention, there is provided a film-forming method, comprising forming a liquid film consisting of a coating solution prepared by adding a solid component to a solvent on the entire surface of a target substrate to be processed; arranging a disk plate having at least one through-hole in the vicinity of the target substrate such that the disk plate is not in contact with the liquid film; rotating the disk plate so as to generate a flow of gas between the target substrate and the lower surface of the disk plate; and bringing the liquid film into contact with the flow of gas so as to remove the solvent from the liquid film, thereby forming a solid phase film consisting of the solid component on the target substrate.
According to a third aspect of the present invention, there is provided a film-forming method, comprising forming a liquid film consisting of a chemical solution prepared by adding a solid component to a solvent on the entire surface of a target substrate to be processed; positioning a disk plate right above and apart from the target substrate such that the disk plate is not brought into contact with the liquid film; maintaining a reduced pressure state in the clearance between the disk plate and the target substrate and around the clearance; rotating the disk plate so as to form an flow of gas in the clearance between the target substrate and the lower surface of the disk plate; and bringing the liquid film into contact with the flow of gas so as to remove the solvent within the liquid film, thereby forming a solid phase film consisting of the solid component on the target substrate.
According to a fourth aspect of the present invention, there is provided a film-forming apparatus, comprising a dispenser nozzle arranged to face a target substrate to be processed so as to supply a chemical solution to the target substrate; a suction nozzle arranged to face the target substrate for sucking a solvent vapor on a liquid film formed on the target substrate by the supply of a chemical solution from the dispenser nozzle; a first moving section for relatively moving the target substrate and the dispenser nozzle; and a second moving section for relatively moving the target substrate and the suction nozzle.
According to a fifth aspect of the present invention, there is provided a liquid film drying apparatus, comprising a disk plate arranged to face a target substrate to be processed, a liquid film containing a solvent being formed on the surface of the target substrate, and having at least one through-hole; a rotary driving section for rotating the disk plate; an flow control plate arranged to face the disk plate on the side of the open portion of the through-hole, which is the side opposite to the side of the target substrate; and an up-down driving section for relatively changing the distance between the disk plate and the target substrate and the distance between the disk plate and the flow control plate.
Further, according to a sixth aspect of the present invention, there is provided a liquid film drying apparatus, comprising a disk plate arranged to face a target substrate to be processed, a liquid film containing a solvent being formed on the surface of the target substrate, and having at least one through-hole; a rotary driving section for rotating the disk plate; and an external gas flow generator for supplying an flow of gas into the through-hole.